This application relates to a system and method for controlling an engine to allow a vehicle operator to manually exceed an established maximum vehicle speed normally imposed by the vehicle""s engine control so that the operator may safely pass other vehicles.
Vehicle engines, and particularly truck engines, are typically controlled by electronic engine control modules which implement various methods of controlling the vehicle engine to optimize the operation of the vehicle. For example, U.S. Pat. No. 5,477,827, assigned to Detroit Diesel Corporation, also the assignee of the present invention, discloses a system and method for controlling an engine including the capability of establishing a normal maximum speed and adding to that maximum speed for a selected time period as a driver performance incentive whenever the driver operates the vehicle within certain established performance goals, such as minimization of idle time, selection of the optimal transmission gear, maintaining a steady throttle, or reducing the use of engine driven accessory loads.
The capability of establishing a normal speed limit provides fleet managers and individual truck owners with the capability of insuring that their truck operators drive safely and meet desired fuel efficiency and other vehicle and engine operation goals. However, programming electronic engine control modules to establish vehicle speed limits which may, for example, maximize fuel efficiency, may otherwise limit the operator""s ability to operate the vehicle in an optimal fashion in an atypical situation, such as an emergency, or when it is desirable to safely pass other vehicles at a speed in excess of the established normal speed limit for the vehicle.
It is therefore an object of the present invention to provide a system and method for controlling an engine which allows the manufacturer, fleet manager, or vehicle owner to establish a normal vehicle speed limit, but which also allows the vehicle operator to exceed that established speed limit to allow the operator to safely pass other vehicles, or otherwise operate the vehicle at a higher speed in an emergency.
It is also an object of the present invention to provide a system and method for controlling a vehicle engine which provides the operator the capability of manually operating the vehicle to exceed the established normal speed limit of the vehicle for a preselected time period, including warning the operator when the period during which the operator can manually override the vehicle speed limit is about to lapse.
In carrying out the above and other objects, the method of the present invention includes establishing a normal vehicle speed limit, establishing a passing duration period, establishing a passing override reset interval, and controlling the engine in response to operator input to provide a vehicle speed exceeding the normal vehicle speed limit for a cumulative passing period not greater than the passing duration period at any time during the passing override reset interval. When implemented on an electronic engine control module, the system and method of the present invention thus allows an operator to override the normal vehicle speed limit imposed, for example, by the vehicle fleet manager, for a limited period of time to allow the vehicle operator to safely pass other vehicles.
In one embodiment, the method of the present invention also includes establishing a passing speed increment. The engine is controlled to allow the operator to increase the vehicle speed beyond the normal speed limit by an amount up to but not exceeding the passing speed increment.
In another embodiment, the method of the present invention also includes establishing a warning period, and issuing a warning to the operator whenever the amount of time that the operator may manually exceed the normal speed limit is less than the warning period. In this embodiment, the warning period is preferably set for an amount of time adequate to allow the vehicle""s operator to complete his passing maneuver and return the vehicle to its normal speed at or below the established vehicle speed limit.
In one embodiment, the method of the present invention includes controlling the engine to gradually reduce the vehicle speed upon the expiration of the passing duration period to cause the vehicle to gradually slow to the normal maximum speed limit.
These and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.